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ftrace/graph: Add ftrace_graph_max_depth kernel parameter

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Early trace callgraphs can be extremely large on systems with
several seconds of boot time. The max_depth parameter limits how
deep the graph trace goes and reduces the output size. This
parameter is the same as the max_graph_depth file in tracefs.

Link: http://lkml.kernel.org/r/1488499935-23216-1-git-send-email-todd.e.brandt@linux.intel.com

Signed-off-by: Todd Brandt <todd.e.brandt@linux.intel.com>
[ changed comments about debugfs to tracefs ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Todd Brandt 2017-03-02 16:12:15 -08:00 committed by Steven Rostedt (VMware)
parent bf7165cfa2
commit 65a50c6562
2 changed files with 15 additions and 0 deletions
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6
Documentation/admin-guide/kernel-parameters.txt
View File

@ -1173,6 +1173,12 @@
functions that can be changed at run time by the functions that can be changed at run time by the
set_graph_notrace file in the debugfs tracing directory. set_graph_notrace file in the debugfs tracing directory.
ftrace_graph_max_depth=<uint>
[FTRACE] Used with the function graph tracer. This is
the max depth it will trace into a function. This value
can be changed at run time by the max_graph_depth file
in the tracefs tracing directory. default: 0 (no limit)
gamecon.map[2|3]= gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port) support via parallel port (up to 5 devices per port)

9
kernel/trace/ftrace.c
View File

@ -4415,6 +4415,15 @@ static int __init set_graph_notrace_function(char *str)
} }
__setup("ftrace_graph_notrace=", set_graph_notrace_function); __setup("ftrace_graph_notrace=", set_graph_notrace_function);
static int __init set_graph_max_depth_function(char *str)
{
if (!str)
return 0;
fgraph_max_depth = simple_strtoul(str, NULL, 0);
return 1;
}
__setup("ftrace_graph_max_depth=", set_graph_max_depth_function);
static void __init set_ftrace_early_graph(char *buf, int enable) static void __init set_ftrace_early_graph(char *buf, int enable)
{ {
int ret; int ret;